Effects of Surface Waviness on Fan Blade Boundary Layer Transition and Profile Loss—Part I: Methodology and Computational Results

Abstract This two-part paper describes a new approach to determine the effect of surface waviness, arising from manufacture composite fan blades, on transition onset location movement and hence profile losses. The includes analysis computations unsteady disturbances in boundary layers over wavy surface, assessed supported by wind tunnel measurements these location. An integrated framework is developed for waviness effects natural transition. framework, referred as extended eN method, traces evolution disturbance energy transfer flow external acoustic noise through exponential growth Tollmien–Schlichting (TS) waves, start end process. computational results show that affects due interaction between TS layer instability strongest when geometric wavelengths match. condition at which this occurs, initial amplitude grow create maximized, called receptivity amplification. provide first-of-a-kind descriptions mechanism changes well quantitative calculations performance wavelength, wave amplitude, initiated blade.